<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        input:checked {
            height: 100px;
        }
        
        a:link {
            color: red;
        }
        
        a:visited {
            color: blue;
        }
        
        .box {
            height: 100px;
            width: 100px;
            background: red;
        }
        
        .box:hover {
            background-color: green;
        }
        /* input[type=text] {
            height: 200px;
        }
        
        input[type=password] {
            height: 100px;
        } */
        
        input[index="1"] {
            height: 100px;
        }
    </style>
</head>

<body>
    <input type="checkbox" />
    <a href="#">超链接</a>
    <div class="box"></div>
    <input type="text" index="2">
    <input type="password" index="1">
    <a href="1">超链接</a>

</body>

</html>